1. Field of the Invention
The present invention relates to a rotary head type tape recording and/or reproducing apparatus. More particularly, the invention relates to a rotary head type tape recording and/or reproducing apparatus in which the position of a tape path for a head drum is correctly restricted.
2. Description of the Prior Art
A tape player for recording and/or reproducing has a running tape in a state in which the tape is wrapped around a head drum, which has a rotary head, at a predetermined wrap angle. If a relative position of the tape for the head drum, in other words, for the rotary head, is not accurately restricted, the linearity and reproducibility of a recording track and a scanning line upon reproduction are lost. Therefore, it is necessary to use means for accurately restricting the relative position of the tape for the head drum.
Accordingly, hitherto, a micro stairway or ledge portion, which is called a lead, is formed on the head drum and the tape is moved in a state in which one of the edges of the tape is slid along the lead.
In FIG. 1, reference character a indicates a head drum of the upper drum rotating type.
A lower drum b is fixed to a chassis (not shown). A lead c is formed as an upward micro ledge or stairway surface on an outer peripheral surface of the lower drum b.
An upper drum d is located so as to overlay an upper side or surface of the lower drum b and is rotatably provided for the lower drum b. A rotary head f is arranged in a notch e formed on an outer peripheral edge of the lower surface of the upper drum d.
A tape g is wrapped around the head drum a at a predetermined wrap angle in a state in which a lower edge of the tape g is in contact with the lead c. The tape g is moved in the direction shown by an arrow. A path of the tape g is restricted by tape guides and the like (not shown). The wrapping operation of the tape g onto the head drum a is started at an angle .theta..sub.2. A moving force in the downward direction is applied to the portion of the tape g which was wrapped around the head drum a by the above components, a tape tension, and the like. Thus, the tape g moves so that its lower edge slides along the lead c.
In FIG. 2, a head drum h is of the type in which an upper drum k and a lower drum i are fixed and a middle drum is rotatable.
The lower drum i is fixed to a chassis (not shown). A lead j is formed on an outer peripheral surface of the lower drum i.
The upper drum k is provided on the upper side of the lower drum i so as to be fixed to the lower drum i. A small gap l is formed between the outer peripheral surfaces of the upper and lower drums k and i.
A middle drum (not shown) is rotatably arranged between the lower and upper drums i and k. A rotary head m is supported on the middle drum. The rotary head m moves in the tape gap l.
The tape g is wrapped around the head drum h at a predetermined wrap angle in a state in which a lower edge of the tape g is in contact with the lead j. Then, the tape g is moved in the direction shown by an arrow. Moving forces indicated by arrows F.sub.1 and F.sub.2 are applied to the tape g. Thus, the tape g is moved in a state in which its lower edge is always in contact with the lead j.
It is necessary to form the leads c and j for both of the foregoing head drums a and h and a high accuracy is required to form the leads c and j, so that the manufacturing costs are high.
On the other hand, in order to allow the tape g to move along the leads c and j, it is necessary to accurately manage the angles .theta..sub.1, .theta..sub.2, the tape tension, the rigidity of the tape, and the magnitudes of forces F.sub.1 and F.sub.2. If the values of .theta..sub.1, .theta..sub.2, F.sub.1 and F.sub.2, are small, the lower edge of the tape g floats from the leads c and j, so that the positions of the tape g for the head drums a and h become unstable. However, if the .theta..sub.1, .theta..sub.2, F.sub.1 and F.sub.2 are too large as compared with the rigidity of the tape g, an accident can occur, such as the lower edge of the tape g being peeled off and deformed or the like. Therefore, it is necessary to very carefully manage the values of .theta..sub.1, .theta..sub.2, F.sub.1 and F.sub.2, the tape tension, the rigidity of the tape, or the like. These factors will cause an increase in the costs of the tape player.